1. Field of the Invention
The present invention relates to a zoom lens system and an electronic image pickup apparatus using the same.
2. Description of the Related Art
A zoom lens system to be applied to an electronic image pickup apparatus such as a digital camera is demanded to have a wide photographing angle of view and a high image forming performance. It is also demanded that a digital zoom function of the image pickup apparatus be combined to enlarge an image of an object very largely. In this case, since the digital zoom function enlarges an only part of an image picked up by an image sensor disposed in the electronic image pickup apparatus by electric processing, an image tends to become coarse. To prevent this, the zoom lens system is demanded to have a certain degree of zooming ratio.
Therefore, the zoom lens system for use in the electronic image pickup apparatus is demanded to have a high image forming performance, a large angle of view in a wide angle end, and a certain degree of or more zooming ratio.
As a compact photographing zoom lens system whose zooming ratio exceeds three-fold and whose angle of view is comparatively large, there is known a lens system described in Japanese Patent Application Laid-Open Nos. 2004-191599 and 2001-42218 and U.S. Patent Application Publication No. 2004/0201902A1.